CN111083405B - Bimodal bionic vision sensor pixel reading system - Google Patents
Bimodal bionic vision sensor pixel reading system Download PDFInfo
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Abstract
The embodiment of the invention provides a pixel reading system of a dual-mode bionic vision sensor, which can realize high-speed transmission of input data and output data of a first class of control circuits by adopting a data input bus of a digital-to-analog converter and a first data output bus to transmit data, thereby improving the image generation speed of the dual-mode bionic vision sensor.
Description
Technical Field
The invention relates to the technical field of integrated circuits, in particular to a pixel readout system of a bimodal bionic vision sensor.
Background
At present, with the continuous and deep research on image sensors and image processing and recognition algorithms, the bionic vision sensor plays an increasingly important role in a plurality of application fields such as industrial manufacturing, intelligent transportation, intelligent robots and the like.
The bionic vision sensor mainly simulates the mode of human retina, and the human retina mainly comprises two visual perception cells, namely cone cells and rod cells, which respectively correspond to two different modes. The mode of the cone cells is mainly sensitive to absolute light intensity information and color information, and the cone cells have high image restoration precision but low restoration speed; in contrast to the mode of the cone cells, the rod cells mainly sense light intensity gradient information, have a fast sensing speed and a large dynamic range of sensing, but cannot sense absolute light intensity information and color information.
However, all the bionic visual sensors in the prior art can only simulate one mode of the retina of the human eye to form a single perception mode, and thus can only perceive a certain kind of information. Like conventional cameras, color information is mainly perceived, similar to cone cells. Such as Dynamic Vision Sensor (DVS), which is similar to rod cells, primarily senses intensity gradient information. And the single-modality visual sensor application scenarios are limited. For example, for a bionic visual sensor similar to a cone cell, since absolute light intensity information rather than light intensity gradient information is obtained by shooting, although the bionic visual sensor is widely applied to household entertainment electronic equipment, in the field of industrial control, the bionic visual sensor is often faced with the problems of insufficient speed, too small dynamic range and the like, and is difficult to apply. For the bionic visual sensor similar to the rod cell, although the sensing speed is high, the bionic visual sensor is only sensitive to a moving object, so that an image is difficult to shoot, or the quality of the shot image is poor, and the requirement of entertainment electronic equipment is difficult to meet. Moreover, the bionic vision sensor only comprises a single perception mode, and the bionic vision sensor fails when the perception mode fails, so that the bionic vision sensor has great limitation on unmanned driving, unmanned aerial vehicles and other robots with high requirements on stability. In addition, the main indexes for evaluating the performance of the bionic vision sensor at present comprise image quality, dynamic range and shooting speed. From the above, under the framework of the traditional bionic visual sensor, the three indexes are often mutually exclusive: if the shooting speed is increased, the dynamic range of the bionic vision sensor is reduced; the shooting speed generally decreases as the image quality improves, and it is difficult to achieve both.
Therefore, it is urgently needed to provide a bionic visual sensor with dual sensing modes, i.e. a dual-mode bionic visual sensor, which can sense absolute light intensity information, color information and light intensity gradient information at the same time, and further provide a pixel reading system matched with the sensor.
Disclosure of Invention
To overcome or at least partially address the above problems, embodiments of the present invention provide a dual-modality biomimetic visual sensor pixel readout system.
The embodiment of the invention provides a pixel reading system of a bimodal bionic vision sensor, which comprises: a digital-to-analog converter data input bus and a first data output bus;
the data input bus of the digital-to-analog converter is connected with the digital-to-analog converter corresponding to the first class control circuit, and the first data output bus is connected with the output end of the first class control circuit; the first type of control circuit is a control circuit corresponding to a first type of target photosensitive device in a pixel array of the bimodal bionic vision sensor;
the target first-class photosensitive device is used for acquiring a target optical signal and converting the target optical signal into a first-class current signal; the first-class control circuit is used for outputting a designated digital signal representing light intensity gradient information in the target optical signal based on a difference value between the first-class current signal and the sum of second-class current signals obtained by converting a first preset number of non-target first-class photosensitive devices around the target first-class photosensitive device.
Preferably, the bimodal biomimetic vision sensor pixel readout system further comprises: an addressing decoder;
the addressing decoder is used for reading out the output result of a second type of control circuit, and the second type of control circuit is a control circuit corresponding to a second type of photosensitive device in the pixel array;
the second type photosensitive device is used for acquiring the target optical signal, extracting an optical signal of a specified frequency band from the target optical signal, and converting the optical signal of the specified frequency band into a third type current signal; the second type control circuit is used for outputting an analog voltage signal representing light intensity information in the target light signal based on the third type current signal.
Preferably, the pixel readout system of the dual-modality bionic vision sensor further comprises: an analog-to-digital converter;
the analog-to-digital converter is connected with the addressing decoder and used for converting the output result of the second control circuit read by the addressing decoder into a digital voltage signal.
Preferably, the pixel readout system of the dual-modality bionic vision sensor further comprises: a second data output bus;
the second data output bus is connected with the analog-to-digital converter.
Preferably, the pixel readout system of the dual-modality bionic vision sensor further comprises: a correlated double sampling circuit CDS;
the CDS is connected between the second-type control circuit and the address decoder.
Preferably, every second preset number of the control circuits of the first type share one digital-to-analog converter.
Preferably, the pixel readout system of the dual-modality bionic vision sensor further comprises: a first storage unit;
the first storage unit is used for storing output results of every second preset number of the first-class control circuits.
Preferably, the pixel readout system of the dual-modality bionic vision sensor further comprises: a second storage unit;
the second storage unit is used for storing the output results of the first type of control circuits stored in all the first storage units.
Preferably, the pixel readout system of the dual-modality bionic vision sensor further comprises: a clock and a phase locked loop;
the clock is connected with the phase-locked loop, and the phase-locked loop is connected with the digital-to-analog converter, the first storage unit and the second storage unit corresponding to the first type of control circuit.
Preferably, the addressing decoder specifically includes: an X-direction addressing decoder and a Y-direction addressing decoder;
the X-direction addressing decoder is used for reading the output result of the second type control circuit corresponding to the second type photosensitive device of each column in the pixel array;
and the Y-direction addressing decoder is used for reading out the output result of the second type control circuit corresponding to the second type photosensitive device of each row in the pixel array.
According to the pixel reading system of the dual-mode bionic vision sensor, the data input bus and the first data output bus of the digital-to-analog converter are adopted to transmit data, so that high-speed transmission of input data and output data of the first class of control circuits can be achieved, and the image generation speed of the dual-mode bionic vision sensor is further improved.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of an arrangement of a pixel array of a bimodal biomimetic visual sensor according to an embodiment of the present invention;
FIG. 2 is a schematic diagram illustrating an arrangement of a pixel array of a bimodal biomimetic visual sensor according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a first type current mode active pixel sensor circuit for controlling a target first type photosensitive device according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a variation of a specified digital signal input to a DAC15 in a first type of current-mode active pixel sensor circuit provided by an embodiment of the present invention;
FIG. 5 is a schematic diagram of a first type of current-mode active pixel sensor circuit according to an embodiment of the present invention;
FIG. 6 is a schematic structural diagram of a pixel readout system of a bimodal biomimetic vision sensor according to an embodiment of the present invention;
fig. 7 is a schematic diagram of a specific structure of a voltage mode active pixel sensor circuit according to an embodiment of the present invention;
FIG. 8 is a block diagram of an address decoder according to an embodiment of the present invention;
FIG. 9 is a schematic diagram of a second type of current-mode active pixel sensor circuit according to an embodiment of the present invention;
FIG. 10 is a schematic diagram of the connection of an address decoder according to an embodiment of the present invention;
fig. 11 is a schematic structural diagram of a CDS provided in an embodiment of the present invention;
fig. 12 is a circuit timing diagram of the CDS according to the embodiment of the present invention;
fig. 13 is a schematic structural diagram of a CDS provided in an embodiment of the present invention;
fig. 14 is a schematic structural diagram of a pixel readout system of a bimodal biomimetic vision sensor according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the embodiments of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience in describing the embodiments of the present invention and simplifying the description, but do not indicate or imply that the referred devices or elements must have specific orientations, be configured in specific orientations, and operate, and thus, should not be construed as limiting the embodiments of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the embodiments of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. Specific meanings of the above terms in the embodiments of the present invention can be understood in specific cases by those of ordinary skill in the art.
The embodiment of the invention provides a pixel reading system of a bimodal bionic vision sensor, which comprises: a digital-to-analog converter data input bus and a first data output bus;
the data input bus of the Digital-to-Analog Converter is connected with a Digital-to-Analog Converter (DAC) corresponding to the first class of control circuit, and the first data output bus is connected with the output end of the first class of control circuit; the first type of control circuit is a control circuit corresponding to a first type of target photosensitive device in a pixel array of the bimodal bionic vision sensor;
the target first-class photosensitive device is used for acquiring a target optical signal and converting the target optical signal into a first-class current signal; the first-class control circuit is used for outputting a designated digital signal representing light intensity gradient information in the target optical signal based on a difference value between the first-class current signal and the sum of second-class current signals obtained by converting a first preset number of non-target first-class photosensitive devices around the target first-class photosensitive device.
Specifically, in the embodiment of the present invention, the pixel array of the dual-mode bionic vision sensor is formed by arranging a plurality of first type photosensitive devices and a plurality of second type photosensitive devices, and specifically, may be formed by arranging the first type photosensitive devices and the second type photosensitive devices alternately. Each first type of photosensitive device and each second type of photosensitive device are respectively used as a pixel. The number of the first type of photosensitive devices and the number of the second type of photosensitive devices may be set according to the size of the pixel array, and may be the same or different, which is not specifically limited in the embodiment of the present invention.
The first type of photosensitive device and the second type of photosensitive device are used for acquiring target optical signals.
The first photosensitive device comprises a target first photosensitive device and a non-target first photosensitive device, the target first photosensitive device is further used for converting a target optical signal into a first current signal, and the non-target first photosensitive device is further used for converting the target optical signal into a second current signal. The first type of photosensitive devices may specifically be photodiodes having the same response curve.
The second type photosensitive device is also used for extracting an optical signal of a specified frequency band from the target optical signal and converting the optical signal of the specified frequency band into a third type current signal. The second type of photosensitive device has photodiodes with different response curves, the response frequency band of the second type of photosensitive device is specifically a designated frequency band, and the designated frequency band can be a red light frequency band, a blue light frequency band or a green light frequency band. The second type of photosensitive device may also be composed of a photodiode and a Color Filter (CF) with the same response curve, where the color Filter may specifically be a red color Filter, a blue color Filter, or a green color Filter, and is used to extract optical signals in a red light band, a blue light band, or a green light band from the target optical signal, respectively. It should be noted that the color filter may specifically be a filter or a lens, and when the color filter is a lens, a bayer lens may be specifically selected, and other types of lenses may also be selected.
In the following embodiments, only the second type of photosensitive device is exemplified by a photodiode and a color filter having the same response curve.
The arrangement of the pixel array of the dual-mode bionic vision sensor can be as shown in fig. 1, and only a 7 × 7 pixel array is shown in fig. 1, and is formed by arranging 25 first-type photoreceptors 11 and 24 second-type photoreceptors 12 alternately. In fig. 1, the reference signs "+" indicate that all the first-type photosensitive devices are target first-type photosensitive devices, the reference signs "-" indicate that all the first-type photosensitive devices are non-target first-type photosensitive devices, and the reference signs R, G, B indicate that all the second-type photosensitive devices extract optical signals in a red frequency band, all the second-type photosensitive devices extract optical signals in a green frequency band, and all the second-type photosensitive devices extract optical signals in a blue frequency band, respectively. For example, a second type of photosensitive device with a red color filter, a second type of photosensitive device with a green color filter, and a second type of photosensitive device with a blue color filter, respectively. The arrangement of the pixel array of the bimodal biomimetic visual sensor may also be as shown in fig. 2, or other arrangements, which are not specifically limited in the embodiment of the present invention.
Each target first-class photosensitive device corresponds to a control circuit, the control circuit corresponding to the target first-class photosensitive device is a first-class control circuit, specifically is a first-class current mode active pixel sensor circuit, and is used for outputting a designated digital signal representing light intensity gradient information in a target optical signal based on a difference value between a first-class current signal and a sum of second-class current signals obtained by converting a first preset number of non-target first-class photosensitive devices around the target first-class photosensitive device. In an embodiment of the invention, the first type of control circuit is used for simulating the action of the excitatory type rod cells.
The first type of control circuit comprises a target first type of photosensitive device, a first current amplifier, a comparator, an adder, a digital-to-analog converter and a three-state gate circuit; the target first-class photosensitive device is connected with the first current amplifier, and the first current amplifier is connected with one input end of the comparator; the input end of the adder is respectively connected with the first type control switch, and the output end of the adder is connected with the other input end of the comparator; the output end of the comparator is connected with the digital-to-analog converter, the digital-to-analog converter converts an input designated digital signal into a designated analog signal and outputs the designated analog signal to the first current amplifier or the adder until the output end of the comparator outputs an event pulse signal, namely the comparator is in an edge trigger state, the first-class current mode active pixel sensor circuit outputs the designated digital signal, and the designated digital signal is used for representing light intensity gradient information in the target light signal.
The tri-state gate circuit is respectively connected with the output end of the comparator and the input end of the digital-to-analog converter; and the tri-state gate circuit is used for outputting the specified digital signal when the output end of the comparator outputs the event pulse signal, namely when the comparator is in an edge triggering state.
As shown in fig. 3, a first type of current mode active pixel sensor circuit for controlling a target first type of photosensitive device is provided in an embodiment of the present invention. The first-class current mode active pixel sensor circuit in fig. 3 includes a target first-class photo-sensing device 11, a first current amplifier 12, a comparator 13, an adder 14, a Digital-to-Analog Converter (DAC) 15, where the target first-class photo-sensing device 11 is connected to the first current amplifier 12, and the first current amplifier 12 is used for converting a first-class current signal I obtained by converting the target first-class photo-sensing device 110Amplifying by a first predetermined amount, i.e. amplifyingThe multiple of the first-class current signal is equal to the number of the non-target first-class light-sensitive devices around the target first-class light-sensitive device 11, so that the sum of the amplified first-class current signal and the second-class current signal converted by the first preset number of non-target second-class light-sensitive devices around the target first-class light-sensitive device 11 is ensured to be in the same order of magnitude. It should be noted that the first photosensitive device provided in the embodiment of the present invention does not extract an optical signal in a specified frequency band from a target optical signal, that is, response curves are the same or no optical filter is present in the first photosensitive device, so that the response frequency band of the first photosensitive device is related to itself.
The first current amplifier 12 is connected to one input terminal of the comparator 13, and inputs the amplified first-type current signal to the comparator 13. The 4 non-target first type photosensitive devices around the target first type photosensitive device 11 are each connected to an input terminal of the adder 14. Since each non-target first type photosensitive device is connected in series with a first type control switch. In the embodiment of the present invention, only the first-type control switch M connected in series with each non-target first-type photosensitive device is shown1、M2、M3、M4。
An output of the adder 14 is connected to another input of the comparator 13. 4 current signals I converted by non-target first-class photosensitive devices1、I2、I3、I4Are respectively inputted to the adder 14, and are inputted to the adder 141、I2、I3、I4The summation is performed, and the summation result is input to the comparator 13. The amplified current signals of the first type are compared by a comparator 13 with the result of the summation by an adder 14. If the comparison result of the current time is consistent with the comparison result of the current time, the DAC15 converts the input designated digital signal into the designated analog signal, outputs the designated analog signal to the first current amplifier 12 or the adder 14, and marks the designated analog signal output to the first current amplifier 12 as IDA2The designated analog signal output to the adder 14 is denoted as IDA1. After being output, the signals are compared by a comparator 13, and when the comparison result of the previous moment and the next moment is opposite, the output of the comparator 13The output end outputs an event pulse signal, that is, the comparator 13 is in an edge triggered state, at this time, the first-class current mode active pixel sensor circuit outputs a specified digital signal, and the specified digital signal is used for representing light intensity gradient information in the target light signal. Wherein the specified digital signal output by the first type of current-mode active pixel sensor circuit is a digital signal represented by 0 and 1. The tri-state gate 41 is connected to the output of the comparator 13 and the input of the DAC15, respectively; the tri-state gate 41 is used to output a specified digital signal when the output terminal of the comparator 13 outputs the event pulse signal, i.e., when the comparator 13 is in an edge triggered state.
The designated digital signal input to the DAC15 may be a manually input designated digital signal that periodically increases, and the variation form of the designated digital signal is specifically as shown in fig. 4, where the designated digital signal is specifically increased in a step-like manner with time, and when a certain time N × step occurs, the designated digital signal takes a value of Δ I, the comparator 13 outputs an event pulse signal, that is, the comparator 13 is in an edge triggered state, and then Δ I at this time is used as the output of the first-type current mode active pixel sensor circuit. Wherein, N is the number of steps passed before, and step is the time length of each step.
Fig. 5 is a schematic diagram of a specific structure of a first type of current-mode active pixel sensor circuit provided in the embodiment of the present invention. In fig. 5, circuit structure 51 simulates a rod cell circuit, and circuit structure 52 simulates a ganglion cell and a bipolar cell. Vcc is the power supply of the control circuit, the target first type photosensitive device 53 is connected to Vcc, and the first type current signal I converted by the target first type photosensitive device 530Amplified by 4 times by a current mirror 54 and then connected with the input end of a Comparator (CP) 56, and the current signals converted by 4 non-target first-type photosensitive devices around the target first-type photosensitive device 53 are I1、I2、I3、I4。
In fig. 5, the current mirror 54 is a first current amplifier. The 4 non-target first type photosensitive devices surrounding the target first type photosensitive device 53 are not shown in fig. 5, but only in series with each non-target first type photosensitive deviceControl switch M of the first kind1、M2、M3、M4。I1、I2、I3、I4The lines are combined into one line to realize the function of the adder. One line of the combination is connected to the input of CP 56. The amplified first class current signal and I are amplified by CP561、I2、I3、I4And comparing the sums. If the comparison result of the current time is the same as that of the current time, no output is made, and the DAC55 converts the input designated digital signal into a designated analog signal and outputs the designated analog signal to the target first-type photosensitive device 53 or one of the non-target first-type photosensitive devices. After the output, the comparison is performed through the CP56, when the comparison result of the previous time and the next time is opposite, the event pulse signal is output from the output terminal of the CP56, that is, the CP56 is in an edge triggered state, and at this time, the specified digital signal is output by the tri-state gate 57.
In fig. 5, a capacitor 58 is further connected between CP56 and ground, where the capacitor 58 may be an actual capacitor, or a parasitic capacitor virtualized in the first type current mode active pixel sensor circuit, which is not limited in the embodiment of the present invention.
As shown in fig. 6, the pixel readout system of the dual-mode bionic visual sensor comprises: a digital-to-analog converter data input bus and a first data output bus; and a data input bus of the digital-to-analog converter is connected with the DAC corresponding to the first class of control circuit, and a first data output bus is connected with the output end of the first class of control circuit. In fig. 6, the Pixel array used is configured by a plurality of sub-Pixel arrays of M rows and N columns, each sub-Pixel array having M × N pixels in total, and pixels (0,0), Pixel (1,0), …, Pixel (N,0), …, and Pixel (N, M), respectively. Each pixel corresponds to 1 photosensitive device, and the arrangement of the photosensitive devices can be as shown in fig. 1 or fig. 2. Each first-type control circuit may correspond to one DAC, or as shown in fig. 6, a plurality of first-type control circuits share one DAC, and the number of the first-type control circuits sharing the DAC is specifically a second preset number, that is, the number of the first-type control circuits corresponding to all target first-type photosensitive devices included in each sub-pixel array.
According to the pixel reading system of the dual-mode bionic vision sensor provided by the embodiment of the invention, the data input bus and the first data output bus of the digital-to-analog converter are adopted to transmit data, so that the high-speed transmission of the input data and the output data of the first class of control circuits can be realized, and the image generation speed of the dual-mode bionic vision sensor is further improved.
On the basis of the foregoing embodiment, the dual-modality bionic visual sensor pixel readout system provided in the embodiment of the present invention further includes: an addressing decoder;
the addressing decoder is used for reading out the output result of a second type of control circuit, and the second type of control circuit is a control circuit corresponding to a second type of photosensitive device in the pixel array;
the second type photosensitive device is used for acquiring the target optical signal, extracting an optical signal of a specified frequency band from the target optical signal, and converting the optical signal of the specified frequency band into a third type current signal; the second type control circuit is used for outputting an analog voltage signal representing light intensity information in the target light signal based on the third type current signal.
Specifically, in the embodiment of the present invention, the control circuit corresponding to the second type of photosensitive device in the pixel array of the dual-mode bionic vision sensor is a second type of control circuit, and the second type of control circuit is specifically a voltage mode active pixel sensor circuit, and is configured to output an analog voltage signal representing light intensity information in the target light signal based on the third type of current signal. As shown in fig. 7, there are 4 second-type photo-sensing devices 71, 72, 73, and 74, respectively, the second-type photo-sensing device 71 is connected in series with the second-type control switch 75 to form a first device branch, the second-type photo-sensing device 72 is connected in series with the second-type control switch 76 to form a second device branch, the second-type photo-sensing device 73 is connected in series with the second-type control switch 78 to form a third device branch, and the second-type photo-sensing device 74 is connected in series with the second-type control switch 77 to form a fourth device branch. The first device branch, the second device branch, the third device branch and the fourth device branch are connected in parallel and then connected with the MOS tubes 79 and 710, and the MOS tube 710 is connected with the MOS tube 711. The MOS tube 79 is used for performing a biasing effect, the MOS tube 710 is used for performing a switching effect, and the MOS tube 711 is used for performing current integration on a third current signal obtained by converting a second photosensitive device on a certain device branch to obtain an analog voltage signal and represent light intensity information in a target light signal.
In the embodiment of the invention, the main function of the addressing decoder is to convert N paths of input data into 2 paths of input dataNThe conversion of (1). As shown in FIG. 8, the N inputs of the address decoder may be the output results of N second-type control circuits, which are respectively denoted as I0、I1、…、IN-1Addressing the decoder 2NThe output is recorded as D0、D1、…、
The address decoder is controlled by a clock Clk and is powered by En.
In the embodiment of the invention, the addressing decoder is introduced to read the output results of the second control circuits, so that the condition that each second control circuit is connected with an output line to output the results can be avoided, resources can be saved, and the data transmission speed is improved.
On the basis of the above embodiment, in the embodiment of the present invention, the control circuit of the bimodal biomimetic visual sensor further includes: and the third control circuit is used for controlling each non-target first type photosensitive device. The third control circuit is in particular a second type of current-mode active pixel sensor circuit. The third control circuit comprises a non-target first type photosensitive device and a second preset number of current mirrors; each current mirror is connected in series with a second type of photosensitive device around the non-target first type of photosensitive device.
Specifically, each second-class current-mode active pixel sensor circuit in the embodiment of the invention controls one non-target first-class photosensitive device.
As shown in fig. 9, the second type of current-mode active pixel sensor circuit comprises a non-target first type photosensitive device 81 and 4 first type current mirrors 82, 83, 84, 85. Each first class current mirror is respectively sensitive to the non-target first class lightA target first type photosensitive device around the device 81 is connected in series, i.e. a current signal I converted from a non-target first type photosensitive device 811Are replicated into 4I1The first-class current mode active pixel sensor circuit, which is respectively used for each target first-class photosensitive device around the non-target first-class photosensitive device 81, acquires light intensity gradient information in a target light signal to realize multiplexing of the non-target first-class photosensitive devices and improve pixel filling factors of the reconfigurable dual-mode bionic vision sensor.
As shown in fig. 10, on the basis of the foregoing embodiment, in the dual-mode bionic visual sensor pixel readout system provided in the embodiment of the present invention, the addressing decoder specifically includes: an X-direction addressing decoder and a Y-direction addressing decoder;
the X-direction addressing decoder is used for reading the output result of the second type control circuit corresponding to the second type photosensitive device of each column in the pixel array;
and the Y-direction addressing decoder is used for reading out the output result of the second type control circuit corresponding to the second type photosensitive device of each row in the pixel array.
Specifically, in the embodiment of the present invention, if the pixel array size of the bimodal biomimetic visual sensor is 640 × 240, the size of each sub-pixel array is 40 × 40. For each sub-pixel array, the value of N in the X-direction addressing decoder is N-10 (log)2640) N in Y-direction addressing decoder is equal to 8 (log)2240). When vertical X access is performed by using an X-direction address decoder or horizontal Y access is performed by using a Y-direction address decoder, the output results of the control circuits corresponding to the pixels in the pixel array are sequentially read by addressing.
On the basis of the foregoing embodiment, the dual-modality bionic visual sensor pixel readout system provided in the embodiment of the present invention further includes: and the ADC is connected with the addressing decoder, and is specifically connected with the X-direction addressing decoder and used for converting output results of the second-type control circuit read by the addressing decoder into Digital voltage signals.
Specifically, in the embodiment of the present invention, for each sub-pixel array, the output result of the second type of control circuit in fig. 7 is the result obtained by current integration performed by the MOS tube 711, and is an analog voltage signal, and an ADC needs to be connected to implement analog-to-digital conversion to obtain a digital voltage signal.
On the basis of the foregoing embodiment, the dual-modality bionic visual sensor pixel readout system provided in the embodiment of the present invention further includes: a second data output bus;
the second data output bus is connected with the analog-to-digital converter.
As shown in fig. 10, on the basis of the foregoing embodiment, the dual-modality bionic visual sensor pixel readout system provided in the embodiment of the present invention further includes: a Correlated Double Sampling (CDS), the CDS is connected between the second type control circuit and the addressing decoder, and may be specifically connected between the second type control circuit and the X-direction addressing decoder, and the CDS is connected to the X-direction addressing decoder through a bus.
Specifically, in the embodiment of the present invention, CDS is adopted for the purpose of reducing the output noise of the second type control circuit. The basic circuit of CDS is shown in FIG. 11, only one device branch of the second type control circuit is shown on the left side, the second type photosensitive device PD and the second type control switch MTGIn series, MTGAnd MOS transistor MRS、MSFConnected, MOS transistor MSFAnd MOS transistor MSELAnd (4) connecting. MOS transistor MRSFor biasing, MOS transistor MSFFor switching, MOS transistor MSELAnd the current integration circuit is used for performing current integration on the third class current signal obtained by PD conversion to obtain an analog voltage signal, representing light intensity information in the target light signal and outputting the analog voltage signal. MRS、MSFThe second capacitor is further connected to a capacitor FD, which may be an actual capacitor or a parasitic capacitor of CDS, and this is not limited in this embodiment of the present invention.
In fig. 11, the right side is CDS, which is composed of two sets of S/H circuits and a differential amplifier, and the specific operation mode is as follows: the reset level and the signal level are sampled and held in the capacitor C respectivelyRAnd a capacitor CSIn, CRRespectively connected with MOS transistor MRAnd MYConnection, CSRespectively connected with MOS transistor MSAnd MYConnecting; are respectively kept at CRAnd CSThe reset level and the signal level in (1) are differentiated to obtain an output signal. The circuit timing diagram of CDS is shown in FIG. 12, FIG. 12
And
respectively representing MOS transistors MSEL、MRSClass II control switch MTGMOS transistor MR、MS、MYOf (c) is detected.
In the signal reading stage, the MOS transistor MSELFrom t1～t7Is always in the on state, thus MSELIs always conducted, and the power supply is always on,
is always at a high level; at t1At time, the ADC reads the reset level and switching noise, then at t2Will be provided with
After being set high (at this time, the capacitor FD is reset)
Stored in a capacitor CR(ii) a At this time, the sample-hold reset signal is in the capacitor CRIn t3Will be provided with
Setting high, and then reading the signal level; at t4By mixing
Put high and beatOn the second kind control switch MTGTransferring the accumulated charge into the capacitance FD; at t5At all times will
Set high, the accumulated charge in the capacitor FD is sampled and held to CSPerforming the following steps; finally, at t6At all times will
The set high enables integration of the accumulation signal and the reset signal.
It should be noted that a schematic structural diagram of the CDS in the embodiment of the present invention may also be shown in fig. 13. Capacitor C1And C2The specific value of (a) may be set as required, which is not specifically limited in the embodiment of the present invention.
On the basis of the foregoing embodiment, the dual-modality bionic visual sensor pixel readout system provided in the embodiment of the present invention further includes: a first storage unit;
the first storage unit is used for storing output results of every second preset number of the first-class control circuits.
Specifically, in the embodiment of the present invention, for each sub-pixel array, there is one first storage unit, which stores the output results of the first type control circuits corresponding to all target first type photosensitive devices in the sub-pixel array. That is, the second predetermined number refers to the number of the first-type control circuits corresponding to all the target first-type photosensitive devices in each sub-pixel array. The first storage unit may specifically be a register, a latch, an SRAM, a DRAM, a memristor, etc.
On the basis of the foregoing embodiment, the dual-modality bionic visual sensor pixel readout system provided in the embodiment of the present invention further includes: a second storage unit;
the second storage unit is used for summarizing output results of the first type of control circuits stored in all the first storage units.
Specifically, in the embodiment of the present invention, a second storage unit exists in the pixel array of the dual-mode bionic vision sensor, and the output results of the first type of control circuit stored in the first storage units in all the sub-pixel arrays in the pixel array are summarized. The second storage unit may specifically be a register, a latch, an SRAM, a DRAM, a memristor, etc.
On the basis of the foregoing embodiment, the dual-modality bionic visual sensor pixel readout system provided in the embodiment of the present invention further includes: a clock and a phase locked loop;
the clock is connected with the phase-locked loop, and the phase-locked loop is connected with the digital-to-analog converter, the first storage unit and the second storage unit corresponding to the first type of control circuit.
As shown in fig. 14, for each sub-pixel array, the sub-pixel array includes M rows and N columns of pixels, and the arrangement of the pixels may be as shown in fig. 1 or fig. 2. The first-class control circuits corresponding to all target first-class photosensitive devices in each sub-pixel array correspond to the same DAC, the input end of the DAC is connected with a data input bus of the digital-to-analog converter, the input of the DAC is DA _ par, and the output of the DAC to each first-class control circuit is DA _ val. And respectively carrying out addressing in the X direction and the Y direction on the first type control circuits corresponding to all target first type photosensitive devices in each sub-pixel array by adopting an X-direction addressing decoder and a Y-direction addressing decoder. The output noise of the control circuits of the second type is also reduced by CDS before addressing in the X direction. The first storage unit stores the output results of the first-type control circuits corresponding to all the target first-type photosensitive devices in the sub-pixel array. The first storage unit is connected with the second storage unit. The second storage unit is connected with the user interface 1 through a first data bus, and the user interface 1 is used for displaying an image formed by the appointed digital signals obtained by the dual-mode bionic vision sensor. On the other hand, the X-direction address decoder is connected to the ADC, and the input of the ADC is AD _ par. The ADC is connected with the user interface 2 through a second data bus, and the user interface 2 is used for displaying an image formed by the digital voltage signals obtained by the dual-mode bionic vision sensor.
FIG. 14 also includes a logic control center for implementing logic control; the system also comprises a user configuration interface for realizing user configuration; the system also comprises a third storage unit used for realizing the storage of the user configuration information. The third storage unit may specifically be a register, a latch, an SRAM, a DRAM, a memristor, or the like. Fig. 14 also includes a clock CLK and a Phase Locked Loop (PLL), where the clock CLK is used to send a clock signal CLK0 to the PLL to implement clock control of the PLL. The clock CLK also sends a clock signal CLK1 to the DAC, a clock signal CLK2 to the first storage unit, a clock signal CLK3 to the second storage unit, a clock signal CLK4 to the ADC, a clock signal CLK5 to the user interface 1, and a clock signal CLK6 to the logic control center through the PLL to implement clocking of the DAC, the first storage unit, the second storage unit, the ADC, the user interface 1, and the logic control center. The input of the DAC and the input of the ADC can be controlled by a logic control center.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (9)
1. A bi-modal biomimetic vision sensor pixel readout system, comprising: a digital-to-analog converter data input bus and a first data output bus;
the data input bus of the digital-to-analog converter is connected with the digital-to-analog converter corresponding to the first class control circuit, and the first data output bus is connected with the output end of the first class control circuit; the first type of control circuit is a control circuit corresponding to a first type of target photosensitive device in a pixel array of the bimodal bionic vision sensor;
the target first-class photosensitive device is used for acquiring a target optical signal and converting the target optical signal into a first-class current signal; the first-class control circuit is used for outputting a designated digital signal representing light intensity gradient information in the target optical signal based on a difference value between the first-class current signal and the sum of second-class current signals obtained by converting a first preset number of non-target first-class photosensitive devices around the target first-class photosensitive device;
further comprising: an addressing decoder;
the addressing decoder is used for reading out the output result of a second type of control circuit, and the second type of control circuit is a control circuit corresponding to a second type of photosensitive device in the pixel array;
the second type photosensitive device is used for acquiring the target optical signal, extracting an optical signal of a specified frequency band from the target optical signal, and converting the optical signal of the specified frequency band into a third type current signal; the second type control circuit is used for outputting an analog voltage signal representing light intensity information in the target light signal based on the third type current signal.
2. The dual-modality biomimetic visual sensor pixel readout system according to claim 1, further comprising: an analog-to-digital converter;
the analog-to-digital converter is connected with the addressing decoder and used for converting the output result of the second control circuit read by the addressing decoder into a digital voltage signal.
3. The dual-modality biomimetic visual sensor pixel readout system according to claim 2, further comprising: a second data output bus;
the second data output bus is connected with the analog-to-digital converter.
4. The dual-modality biomimetic visual sensor pixel readout system according to claim 1, further comprising: a correlated double sampling circuit CDS;
the CDS is connected between the second-type control circuit and the address decoder.
5. The dual-modality biomimetic visual sensor pixel readout system according to claim 1, wherein one of the digital-to-analog converters is shared for every second predetermined number of the first-type control circuits.
6. The dual-modality biomimetic visual sensor pixel readout system according to claim 5, further comprising: a first storage unit;
the first storage unit is used for storing output results of every second preset number of the first-class control circuits.
7. The dual-modality biomimetic visual sensor pixel readout system according to claim 6, further comprising: a second storage unit;
the second storage unit is used for summarizing output results of the first type of control circuits stored in all the first storage units.
8. The dual-modality biomimetic visual sensor pixel readout system according to claim 7, further comprising: a clock and a phase locked loop;
the clock is connected with the phase-locked loop, and the phase-locked loop is connected with the digital-to-analog converter, the first storage unit and the second storage unit corresponding to the first type of control circuit.
9. The dual-modality biomimetic visual sensor pixel readout system according to claim 1, wherein the addressing decoder specifically comprises: an X-direction addressing decoder and a Y-direction addressing decoder;
the X-direction addressing decoder is used for reading the output result of the second type control circuit corresponding to the second type photosensitive device of each column in the pixel array;
and the Y-direction addressing decoder is used for reading out the output result of the second type control circuit corresponding to the second type photosensitive device of each row in the pixel array.
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| CN108200362B (en) * | 2017-12-19 | 2019-10-18 | 清华大学 | Bionical retina imaging circuit and sub-circuit based on space contrast degree |
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